Constrictable tube valve

ABSTRACT

Clamps disposed at opposite sides of a tube of PTFE resin or other crack sensitive material maintain regions at each side of the tube in constantly constricted fluid sealing condition free from crack inducing flexure secured in sealing embrace about a smoothly curving filler piece. In combination with a pair of compressor members there is thus provided a constrictable tube valve having a tube of crack sensitive material which wild not crack upon valve manipulation.

1451 May15,l973

United States Patent 1191 Press FOREIGN PATENTS OR APPLICATIONSCONSTRICTABLE TUBE VALVE [75] Inventor: Irving D. Press, West Orange,NJ. 3/1966 g 7 3 A ee: Res'stotlex Co oration R l d 504'449 8/1930Germany 1 rp ose 693,028 6/l953 GreatBritain............................

[ Filed; MIIP- 1971 Primary Examiner-Martin P. Schwadron AssistantExaminer-Richard Gerard A ttorney- Robert M. Freeman 211 App]. 110.;126,436

[57] ABSTRACT Clamps disposed at opposite sides of a tube of PTFE resinor other crack sensitive material maintain regions at each side of thetube in constantly constricted fluid sealing condition free from crackinducing flex- .251/8, 251/4 [51] Int. 7/06 [58] FieldofSearch..............................25l/4-l0 [56] References Cited UNITEDSTATES PATENTS ure secured in sealing embrace about a smoothly curvingfiller piece. In combination with a pair of compressor members there isthus provided a constrictable tube valve having a tube of cracksensitive material which wild not crack upon valve manipulation. 1

Hyde.......... Nordell................................

"m M c y R 39 7774 9989 .1111 ///l 004 III 17 Claims, 8 Drawing FiguresPATENTED 1 W3 SHEET 1 OF 3 MENTOR,

CONSTRICTABLE TUBE VALVE The present invention relates to fluid valvesand, more particularly, to a valve of the type in which a constrictabletube is mechanically flattened to form a barrier to the flow of fluidmaterial therethrough.

Valves relying upon the construction of a flexible tube have generallybeen referred to in the past as pinch valves. In their most rudimentaryform they incorporate a clamp for literally pinching the flexible tubewith which they are associated in order to occlude the passage of fluidtherethrough. The well known hose clamp employed in every chemicallaboratory is a valve of this type.

In its more refined form, the constrictable tube valve is tailored to aspecial purpose and may be quite complicated. While valves of the typewherein an orifice is blocked or controlled by a valve element are morecommon and more generally used, there are special circumstances underwhich a constrictable tube valve is preferable. For example, theconstrictable tube valve is desirable where it is required to controlthe flow of fluids containing solid particles in substantial quantity orwhere corrosive fluids are involved. Particularly, in the case ofcorrosive fluids, the constrictable tube valve provides a convenientarrangement for isolating the fluid flow path from the operatingmechanism of the valve and from other parts that might be attacked bythe corrosive fluid.

Currently, one of the best, if not the best, corrosion resistantnon-metallic materials is polytetrafluoroethylene resin, hereinafterreferred to as PTFE. This resin is substantially inelastic and, in thethicknesses normally encountered in tube construction, is relativelycrack sensitive. That is, in the usual thicknesses, a thin walledsection of PTFE resin will crack when folded upon itself. Even if acrack does not develop the first time a fold is introduced in a sectionof the resin, cracks will develop if the folding operation is repeatedmore than a few times. Because of this characteristic, it has,heretofore, not been possible to produce a satisfactory constrictabletube type valve where the tube has been made of PTFE resin.

The cracking problem is not new -to valves of this general type. Almostone hundred years ago there was described in US. Pat. No. 143,907 avalve of the constrictable type wherein the tube was made ofindiarubber. The central part of the tube was made elliptical and withsharp internally projecting tongues in the corners for the purpose ofallowing the two flat sides of the elliptical part of the tube to bepressed close together and to form a perfectly tight joint in thecorners without danger of breaking the tube in those places. Morerecently, in US. Pat. No. 1,683,322 there is described a valve of thisgeneral type wherein the control tube is preferably molded to oblongcross-sectional form at its middle portion and, in order that the upperand lower walls may be brought into contact with each other closelyadjacent the hinge line without excessive local flexure and strain, thewalls are formed adjacent the hinge line with relatively thick, inwardlybulged zones so that the lining, when uncollapsed, has a passage whichin cross-section is oblong, with reverse curves in its outline adjacentits extremities.

Unfortunately, in analyzing these prior attempts to solve the crackproblem in connection with rubber or rubber-like tubing, it wasdiscovered that they all were 2 l characterized by some point or pointswhere excessive stress is developed during the closure of the valve. Inaddition, the techniques require special molding of the tubing, acircumstance not readily adaptable to PTFE resin. Thus, prior knowntechniques have not permitted a satisfactory valve to be constructedemploying PTF E resin as the constrictable tube.

With the foregoing problems in mind, it is a primary object of thepresent invention to provide a constrictable tube type valve employing atube of PTF E resin or similar substantially inelastic flexiblegenerally cracksensitive plastic. A concomitant object is to providesuch a valve capable of operating with relatively high fluid pressuresand having a useful life of many thousands of operating cycles. Anancillary object is to extend the operating life of constrictable tubevalves made with any flexible material even an elastomer.

The present invention is predicated upon the discovery that thedifficulty in producing a constrictable tube valve with a PTFE resintube using heretofore known techniques resides in the very pinching fromwhich the pinch valve derives its name. Hence, it is a further object ofthe present invention to provide a constrictable tube valve whereinliteral pinching of the tube is completely avoided. Reliance is had uponconstriction or compression of the tube wall without pinching.

In accordance with one aspect of the present inven tion, there isprovided a valve of the type in which a constrictable tube ismechanically flattened to form a barrier to the flow of fluid materialtherethrough which incorporates the improvement comprising, in additionto the constrictable tube, means disposed at opposite sides of the tubefor maintaining a region at each side in constantly constricted fluidsealing condition. In addition, mechanical compressor means are providedfor adjustably constricting the remainder of the tube between saidregions for controlling the closing of the valve. More particularly, themeans disposed at the opposite sides of the tube comprise at each side afluid impervious filler piece disposed on the interior of the tube andmeans securing the corresponding side of the tube in fluid sealingembrace about the tiller piece.

The invention will be better understood after reading the followingdetailed description of a presently preferred embodiment thereof withreference to the appended drawings wherein:

FIG. 1 is a plan view of a valve embodying the invention;

FIG. 2 is a transverse sectional 'view taken along line 2--2 in FIG. llshowing the valve in closed condition;

FIG. 3 is a view similar to FIG. 2 showing the valve in open condition;

FIG. 4 is a fragmentary longitudinal sectional view taken along line 4-4in FIG. 2;

FIG. 5 is a fragmentary sectional view taken along line 5-5 in FIG. 3;

FIG. 6 is an enlarged fragmentary sectional view showing one side of thetube with a filler piece in place and clamping means thereabout when thevalve is in open condition;

FIG. 7 is a view similar to FIG. 6 when the valve is in closedcondition; and

FIG. 8 is an exploded perspective view of a preferred filler piece and aclamp as used in the valve illustrated in the other figures.

The. same reference numerals are used throughout the drawings todesignate the same or similar parts.

Referring now to the drawings, a valve housing is shown generally atconsisting of two halves 11 and 12 joined along the longitudinal line 13(best seen in FIG. 1) by the bolts 14 and 15 and similar bolts (notseen) on the underside of the valve as viewed in FIG. 1. Disposedbetween the end flanges 16 and 17 of the housing 10 is a constrictabletube 18. While the tube 18 need not be monolithic and may be made ofother materials, it is in this example formed from a single layer of PTFE. A suitable PTFE tube may be produced employing the method set forthin U.S. Pat. No. 2,752,637 issued July 3, I956, and assigned to the sameassignee as the present application. The ends of the tube 18 may beflared at 19 and 20 over the faces of the corresponding flanges l6 and17, respectively. While the present invention can be used advantageouslywith most any wall thickness, it is contemplated that the tube 18 whenformed from PTFE resin will have a wall thickness preferably at least0.040 inches.

Disposed at opposite sides of the tube 18, on the interior thereof, arefiller pieces 21 and 22. These pieces must be fluid impervious elements.The filler piece should have a smoothly curving contour to which thetube may be conformed by wrapping therearound without inducing a crackin the tube wall. As best seen in FIGS. 6 and 7, the filler piecepreferably is in the form of a cylinder with a directrix ofsubstantially tear-drop shape such that the piece has substantially afeatheredge at 23. As shown in FIG. 8, the filler piece is generallytrapezoidal in outline. The filler piece is installed in the tube suchthat when the tube is wrapped around the filler piece the featheredge 23faces radially inwardly of the tube. The filler piece is preferablyproduced from sintered PTF E resin fabricated by any known method.

To permanently constrain the side edge of the tube around the fillerpiece, there is provided the clamping devices 24 and 25. These clampingdevices 24 and 25 may be made up of individual members 26, 27 and 28,29, respectively, which when secured together form two substantiallyC-shape assemblies with the side of the tube being confined by the jawsof the C-shape assembly in sealing engagement with the filler piece. Asbest seen in FIG. 8, the clamp members 26, 27, 28 and 29 may all beidentical being provided with a through bore 30, optionallycounterbored, and a tapped bore 31 on opposite sides thereof. Thus, whentwo of the members are clamped together, face-to-face, the bore 30 inone member will receive a bolt which will thread into the threaded bore31 in the mating member and vice versa. As best seen in FIGS. 6 and 7,the clamp members 26 through 29 should have a jaw configurationfollowing the smooth curve such as 32 in FIG. 6 in order to tightlyembrace the tube 18 around the filler piece 22. In the preferredconstruction shown in FIG. 6, the jaw line 32 will be tear-drop shapedsimilar to the configuration of the filler piece.

As seen in FIG. 6, the clamp members 26 and 27 maintain the tube inconstantly sealed condition from the bight point at 33 to the point 34where the inner surfaces of the tube 18 part. For adjustablyconstricting the remainder of the tube between the end regions there isprovided an upper compressor member 35 and a lower compressor member 36having straight surfaces 37 and 38, respectively, for compressing thetube therebetween. As best seen in FIGS. 2 and 3, the compressors 35 and36 are generally trapezoidal in shape where they come between the endclamps 24 and 25 in order to sealingly compress the tube as shown inFIG. 7.

The compressor 36 may be formed integral with a heavy yoke member 39.The yoke 39 is supported on a threaded shaft 40 along an upper portionprovided with the right-hand threads at 41. The shaft 40 is provided atits lower end with a left-hand threaded section 42 which threadedlyengages the compressor member 35. Guide pins 43 and 44 are secured inthe upper end of the yoke 39 and slide in bores 45 and 46, respectively,in the compressor member 35 for guiding and preventing rotation of thelatter. Pins 47, 48, 49 and 50 installed in the side walls of the valvehousing 10 straddle the side arms of the yoke 39 for guiding it in itsmovement without permitting rotation thereof.

The stem 40 is joumaled in an aperture in the housing 10 and providedwith a suitable handle 51. It should be appreciated from comparing FIGS.2 and 3 that as the handle 51 is rotated in a clockwise or right-handdirection when viewed from the top, it causes the yoke 39 to move upwardtoward the handle while causing the compressor 35 to move downward awayfrom the handle. With this action the valve is closed. When the handle51 is rotated in the opposite direction, the reverse operation takesplace with the valve opening. It will be understood that normally thefluid pressure within the valve will cause the tube to expand when thecompressors are apart as shown in FIG. 3.

From a comparison of FIGS. 6 and 7, it should be readily apparent thatthe tube wall 18 experiences maximum flexing in the vicinity of theregion 52. It should also be apparent that the tube leaves the clamps ina gradually curving configuration resulting in minimal stress during theflexure thereof. Thus, no part of the tube wall is subjected to severestress during the operating life of the valve. Hence, the cracksensitivity of the material is no longer a significant problem.

As best seen in FIGS. 6 and 7, the featheredge 23 of the filler piece islocated slightly inboard of the outer edge 53 of the clamp. The relativepositioning of the featheredge 23 with respect to the outer edge of theclamp is not critical, however. It may be located either inboard,coincident, or outboard, depending upon the clamping force availablefrom the cooperating compressor members.

While the term featheredge is employed in describing the edge 23 of thefiller piece, it is not intended to imply that the edge must necessarilybe paper thin. The thinner the edge the easier it is to establish a sealin the immediate vicinity where the inner surfaces of the tube wall arebrought together. In practice the edge 23 may have significant thicknessso long as the material of the tube or filler piece can be deformed ordisplaced sufficiently during closure of the valve to insure sealing.With a PT FE resin tube it is presently preferred that edge 23 haveminimal thickness.

It should be apparent from the foregoing description that the inventionbecause of the flexing geometry will serve to extend the life of aconstrictable tube valve made with any flexible material, even anelastomer. The arrangement can be used with especial advantage with allcrack-sensitive flexible materials, not only PTFE resin. It is alsocontemplated that the tube of flexible material may be reinforced withone or more layers of reinforcing material.

Having described a presently preferred embodiment of the invention, itwill be understood that various changes may be made in the constructionthereof with out departing from the true spirit of the invention as defined in the appended claims.

What is'claimed is:

1. In a valve of the type in which a constrictable tube is mechanicallyflattened to form a barrier to the flow of fluid material therethrough,the improvement comprising a constrictable tube, external clamping meansdisposed at opposite sides of said tube for maintaining a region at eachside in constantly constricted fluid sealing condition, and mechanicalcompressor means for adjustably constricting the remainder of saidtubebetween said clamping means for controlling the C105- ing of said valvesuch that the entire remainder of said tube at least along a linebetween said clamping means is substantially engaged by said compressormeans in a closed position.

2. A valve according to claim 1, wherein said means disposed at oppositesides of said tube.comprises at each side a fluid impervious elementlocated on the interior of said tube with said clamping means securingthe corresponding side of said tube in fluid sealing embrace about saidelement.

3. A valve according to claim 1, wherein said means disposed at oppositesides of said tube comprises at each side a separate fluid imperviousfiller piece disposed on the interior of said tube with said clampingmeans securing the corresponding side of said tube in fluid sealingembrace about said filler piece.

4. A valve according to claim 3, wherein said tube is wrapped aroundsaid filler piece so as to close upon itself and is so constrained bysaid clamping means, said filler piece having a smoothly curving contourto which said tube conforms.

5. A valve according to claim 3, wherein said filler piece is in theform of a cylinder with a directrix of substantially tear-drop shapesuch that the piece has substantially a featheredge, said tube beingwrapped around said filler piece and maintained in sealing engagementtherewith with said featheredge facing radially inwardly of the tube.

6. A valve according to claim 5, wherein said tube includes at least alining layer of a substantially inelastic flexible generally cracksensitive plastic.

7. A valve according to claim 6, wherein said plastic ispolytetrafluoroethylene resin.

8. A valve according to claim 7, wherein said filler piece is formedfrom polytetrafluoroethylene resin.

9. A valve accordingto claim 8 wherein each of said clamping meanscomprises two members which when secured together form a substantiallyC-shape assembly having a jaw configuration which is similar to theshape of said filler piece.

10. A valve according to claim 3, wherein said tube includes at least alining layer of a substantially inelastic flexible generally cracksensitive plastic.

1 l. A valve according to claim 10, wherein said plastie ispolytetrafluoroethylene resin.

12. A valve according to claim 11, wherein said filler piece is formedfrom polytetrafluoroethylene resin.

13. A valve according to claim 3, wherein each of said clamping meanscomprises two members which when secured together form a substantiallyC-shape assembly, the side of said tube being confined by the jaws ofthe C-shape assembly in sealing engagement with said filler piece.

14. A valve according to claim 3, wherein said tube includes at least alining layer of a substantially inelastic flexible generally cracksensitive plastic, said tube being wrapped around said filler piece soas to close upon itself and being so constrained by said clamping means,and said filler piece is characterized by a smoothly curving contour towhich said tube conforms.

15. A valve according to claim 14, wherein said plastic ispolytetrafluoroethylene resin.

16. A valve according to claim 15, wherein said filler piece is formedfrom polytetrafluoroethylene resin.

17. In a valve of the type in which a constrictable tube is flattened toform a barrier to the flow of fluid material therethrough, theimprovement comprisinga constrictable tube, means disposed at oppositesides of said tube for maintaining a region at each side in constantlyconstricted fluid sealing condition, said means including at each sideof said tube a separate fluid impervious filler piece disposed on theinterior of said tube and a clamping device disposed on the exterior ofsaid tube, said clamping device being constructed and arranged toconstrict the side of said tube about said filler piece in fluid sealingembrace, and means for adjustably constricting the remainder of saidtube between said regions for controlling the closing of said valve.

1. In a valve of the type in which a constrictable tube is mechanicallyflattened to form a barrier to the flow of fluid material therethrough,the improvement comprising a constrictable tube, external clamping meansdisposed at opposite sides of said tube for maintaining a region at eachside in constantly constricted fluid sealing condition, and mechanicalcompressor means for adjustably constricting the remainder of said tubebetween said clamping means for controlling the closing of said valvesuch that the entire remainder of said tube at least along a linebetween said clamping means is Substantially engaged by said compressormeans in a closed position.
 2. A valve according to claim 1, whereinsaid means disposed at opposite sides of said tube comprises at eachside a fluid impervious element located on the interior of said tubewith said clamping means securing the corresponding side of said tube influid sealing embrace about said element.
 3. A valve according to claim1, wherein said means disposed at opposite sides of said tube comprisesat each side a separate fluid impervious filler piece disposed on theinterior of said tube with said clamping means securing thecorresponding side of said tube in fluid sealing embrace about saidfiller piece.
 4. A valve according to claim 3, wherein said tube iswrapped around said filler piece so as to close upon itself and is soconstrained by said clamping means, said filler piece having a smoothlycurving contour to which said tube conforms.
 5. A valve according toclaim 3, wherein said filler piece is in the form of a cylinder with adirectrix of substantially tear-drop shape such that the piece hassubstantially a featheredge, said tube being wrapped around said fillerpiece and maintained in sealing engagement therewith with saidfeatheredge facing radially inwardly of the tube.
 6. A valve accordingto claim 5, wherein said tube includes at least a lining layer of asubstantially inelastic flexible generally crack sensitive plastic.
 7. Avalve according to claim 6, wherein said plastic ispolytetrafluoroethylene resin.
 8. A valve according to claim 7, whereinsaid filler piece is formed from polytetrafluoroethylene resin.
 9. Avalve according to claim 8, wherein each of said clamping meanscomprises two members which when secured together form a substantiallyC-shape assembly having a jaw configuration which is similar to theshape of said filler piece.
 10. A valve according to claim 3, whereinsaid tube includes at least a lining layer of a substantially inelasticflexible generally crack sensitive plastic.
 11. A valve according toclaim 10, wherein said plastic is polytetrafluoroethylene resin.
 12. Avalve according to claim 11, wherein said filler piece is formed frompolytetrafluoroethylene resin.
 13. A valve according to claim 3, whereineach of said clamping means comprises two members which when securedtogether form a substantially C-shape assembly, the side of said tubebeing confined by the jaws of the C-shape assembly in sealing engagementwith said filler piece.
 14. A valve according to claim 3, wherein saidtube includes at least a lining layer of a substantially inelasticflexible generally crack sensitive plastic, said tube being wrappedaround said filler piece so as to close upon itself and being soconstrained by said clamping means, and said filler piece ischaracterized by a smoothly curving contour to which said tube conforms.15. A valve according to claim 14, wherein said plastic ispolytetrafluoroethylene resin.
 16. A valve according to claim 15,wherein said filler piece is formed from polytetrafluoroethylene resin.17. In a valve of the type in which a constrictable tube is flattened toform a barrier to the flow of fluid material therethrough, theimprovement comprising a constrictable tube, means disposed at oppositesides of said tube for maintaining a region at each side in constantlyconstricted fluid sealing condition, said means including at each sideof said tube a separate fluid impervious filler piece disposed on theinterior of said tube and a clamping device disposed on the exterior ofsaid tube, said clamping device being constructed and arranged toconstrict the side of said tube about said filler piece in fluid sealingembrace, and means for adjustably constricting the remainder of saidtube between said regions for controlling the closing of said valve.